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Ligand binding specificities and signal transduction pathways of Fc gamma receptor IIc isoforms: the CD32 isoforms expressed by human NK cells.
- Source :
-
European journal of immunology [Eur J Immunol] 1999 Sep; Vol. 29 (9), pp. 2842-52. - Publication Year :
- 1999
-
Abstract
- We recently reported that human NK cells express, in addition to CD16 [Fcgamma receptor (FcgammaR) IIIA], a second type of FcgammaR, namely CD32 (FcgammaRII). Molecular characterization of CD32 transcripts expressed by highly purified NK cells revealed that they predominantly express products of the FcgammaRIIC gene. Using stable Jurkat transfectants we have analyzed the functional properties of two FcgammaRIIc-specific isoforms isolated from NK cells, namely FcgammaRIIc1 and FcgammaRIIc3, which differ in their cytoplasmic tails. The ligand binding specificity for both murine and human IgG isotypes was found to be similar to that observed for FcgammaRIIb isoforms. Immunoprecipitation studies of FcgammaRIIc isoforms expressed in Jurkat cells revealed a protein of around 40 kDa for FcgammaRIIc1, and a protein of around 32 kDa for FcgammaRIIc3. Signal transduction studies performed on FcgammaRIIc1-expressing Jurkat cells indicated that this molecule is functional, i. e. capable of Ca2+ mobilization and activation of Lck, Zap-70 and Syk protein tyrosine kinases, although the CD3 zeta chain was not found to functionally associate with FcgammaRIIc1. In contrast, FcgammaRIIc3 transfectants showed an impaired ability of this molecule to mobilize Ca2+, but activation of Lck was detected following activation via FcgammaRIIc3. These studies demonstrate the functional activity of FcgammaRIIc isoforms and suggest that the presence of CD32, in addition to CD16, on NK cells may have functional relevance.
- Subjects :
- Antigens, CD biosynthesis
Antigens, CD chemistry
Cross-Linking Reagents
Enzyme Activation
Humans
Jurkat Cells
K562 Cells
Killer Cells, Natural chemistry
Killer Cells, Natural enzymology
Killer Cells, Natural immunology
Ligands
Lymphocyte Specific Protein Tyrosine Kinase p56(lck) metabolism
Phosphorylation
Protein Binding immunology
Protein Isoforms biosynthesis
Protein Isoforms chemistry
Protein Isoforms metabolism
Receptors, IgG biosynthesis
Receptors, IgG chemistry
Tumor Cells, Cultured
Tyrosine metabolism
U937 Cells
Antigens, CD metabolism
Epitopes metabolism
Killer Cells, Natural metabolism
Receptors, IgG metabolism
Signal Transduction immunology
Subjects
Details
- Language :
- English
- ISSN :
- 0014-2980
- Volume :
- 29
- Issue :
- 9
- Database :
- MEDLINE
- Journal :
- European journal of immunology
- Publication Type :
- Academic Journal
- Accession number :
- 10508259
- Full Text :
- https://doi.org/10.1002/(SICI)1521-4141(199909)29:09<2842::AID-IMMU2842>3.0.CO;2-5